Metals in aqueous solutions are difficult to recover when these solutions also contain chelating agents which have a high affinity for the metal, thus, keeping it in solution and preventing its precipitation. It is necessary, therefore, to find some means of decomposing the chelates (complexes), thereby separating the metal ions from the chelant moiety. One such method involves ozonation in combination with ultraviolet light. This is found in U.S. Pat. Nos. 4,289,594 and 4,512,900 which describe methods for treating liquid wastes containing copper ions and complexing agents therefor. The process steps of the latter patent include reducing the copper ions to a concentration of less than 8 ppm, treating with H.sub.2 O.sub.2 followed by ozonation with simultaneous irradiation with ultraviolet light. Another method using ozone and hydrogen peroxide to treat photographic wastes is disclosed in U.S. Pat. No. 4,332,687.
Another literature reference, "Ozonation Rate of Water-soluble Chelates and Related Compounds", J. Chem. Eng. Japan 19, 294 (1986) describes the rates of ozonation for various chelates including Cu, Zn, Ni and Co chelates of ethylenediaminetetraacetic acid.